chore(deps): update dependency execa to v3 (#772)

Author: renovate-bot

samples/package.json

@@ -18,7 +18,7 @@
     "express": "4.17.1"
   },
   "devDependencies": {
-    "execa": "^2.0.0",
+    "execa": "^3.0.0",
     "mocha": "^6.0.0"
   }
 }